Fluorine containing polyethers

Abstract

A fluorinated polyether is synthesized by (1) reacting perfluoroglutryl chloride and 1,5-hexafluoropentane diol to provide a fluorinated polyester and (2) converting ester groups of the polyester to ether groups by SF 4 reduction. The product obtained is a thermally stable polyether which is particularly useful in providing an elastomeric material for aircraft fuel tank sealants, tire valves, O-rings, hose, gaskets, and the like.

I claim: 
     
       1. A process for preparing a fluorine-containing polyether which comprises the steps of: a. reacting perfluoroglutaryl chloride with 1,5-hexafluoropentane diol in the presence of a catalytic amount of dimethylformamide so as to obtain a fluorinated polyester; and   b. reacting the fluorinated polyester with sulfur tetrafluoride in the presence of hydrogen fluoride, thereby obtaining a fluorine-containing polyether product.   
     
     
       2. The process according to claim 1 in which substantially equimolar amounts of perfluoroglutaryl chloride and 1,5-hexafluoropentane diol are reacted in the presence of about 0.5 to 10 milliliters of dimethylformamide per mole of either of the aforementioned reactants at a temperature ranging from about room temperature to 200° C. for a period of about 1 to 24 hours. 
     
     
       3. The process according to claim 2 in which the fluorinated polyester is reacted with a molar excess of sulfur tetrafluoride in the presence of 0.5 to 2 moles of hydrogen fluoride per mole of polyester at a temperature in the range of about 50° to 160° C. for a period of about 2 to 24 hours.